A. Field of the Invention
The present invention relates to a new and improved electric liquid heater and particularly to a new and improved compartmentalized electric water heater that provides substantial energy savings.
B. Description of the Background Art
In prior art domestic water heating tanks a large quantity of water is heated continuously to maintain an entire tank capacity of water at delivery temperature i.e. 140.degree.-160.degree. F. Even when the hot water is not being used, energy must be used to maintain the entire tank capacity of water at delivery temperature by adding energy lost to the atmosphere upon standing. When hot water is used from such prior art hot water tanks, cold water is added directly to the heated water and the cold and hot water mixes freely lowering the delivery temperature of the water. This type of heating by maintaining a large quantity of hot water at delivery temperature regardless of when such hot water will be used, and without regard to the quantity of hot water needed at any particular time is very inefficient and wastes substantial energy which is lost to the surrounding atmosphere at a lower ambient temperature than the water delivery temperature. The present state of the art provides thermal insulation of varying degrees to reduce the energy loss to the atmosphere but does not provide a hot water heater capable of inhibiting uncontrolled, spontaneous mixing of incoming cold water with standing hot water as well or the capability of heating water to its delivery temperature as it approaches the delivery point.
Attempts have been made to reduce the size of hot water heaters while maintaining sufficient capacity by using immersed electric heater elements in place of oil or gas heating. The immersed heating elements provide faster water heating than fossil fuel heating because of the immersion of the heating elements directly in the path of the flowing water. Examples of electric immersion water heaters are disclosed in the Pastore Pat. No. 3,586,822 and in the Swoyer Pat. No. 2,987,604. Another example of an electric immersion hot water heater is disclosed in the Flanders Pat. No. 3,952,181. In accordance with the Flanders patent, one or more of the electric heating elements can be deactivated in accordance with the water demand at any given time. None of these patents have energy savings as their stated objective.
The electric immersion hot water heaters, such as disclosed in the Swoyer and Flanders patents, have not achieved appreciable commercial success, even with controlled deactivation of heating elements, as disclosed in the Flanders patent. It has been determined that one of the basic deficiencies of typical hot water heaters is that the heater structure does not include a relatively long water flow and/or heat conduction path to provide sufficient isolation between the incoming cold water and the outgoing hot water. Without this relative isolation and the long path the heated water freely mixes with the incoming cold water which causes rapid temperature deterioration of the heated water standing in the tank. Due to this free mixing of water, the conventional heaters having compartmentless tanks will deliver only part of the total tank capacity of hot water. The present invention will allow the heater to deliver total tank capacity at design delivery temperature.